The present invention relates to an apparatus for vaporizing a liquid and, more particularly, to a vaporizer that receives carrier gas and vaporizes a liquid anesthetic agent with that carrier gas to produce a stream of carrier gas containing a known concentration of anesthetic agent for introduction into a patient.
There are, of course, various methods and means of vaporizing anesthetic agents to provide an anesthetizing gas to a patient. Typical of one of the types, include that described in U.S. Pat. No. 4,059,657 of Hay. More recently, with the introduction of an anesthetic agent having a relatively low boiling point, newer methods of vaporizing anesthetic agents have been devised and one such method and apparatus is described in U.S. Pat. No. 5,146,915 of Montgomery.
In the typical current anesthetic vaporizers, the unit contains a sump where liquid anesthetic is maintained and which also includes various wicks that provide a surface for enhancing the vaporization of that anesthetic. An inlet receives the carrier gas from a pressurized source, and generally, the stream of carrier gas is divided in the vaporizer such that a main stream of carrier gas continues toward the outlet while a bypass stream is diverted from the main stream and which enters the vaporizing chamber and picks up anesthetic vapor from the sump and wick arrangement. That bypass stream, now saturated with anesthetic later recombines with the main stream of carrier gas to pass through the outlet to be administered to a patient.
Control of the amount of anesthetic vapor in such vaporizers is accomplished by changing the amount of flow in the bypass flow path as a proportion of the carrier gas that passes through the vaporizer. As can be seen with reference to the cited prior art patents, the vaporizers, therefore, required a sump and which had to be at least of sufficient volume to contain enough liquid anesthetic to be used in the operating room during an operation. In addition, the mass of the vaporizers was also somewhat large to maintain, to the extent possible, a constant temperature throughout the operation of the vaporizer.
Such vaporizers are limited to relatively low flows due to the need to saturate the by pass stream with liquid agent before recombining with the main stream of carrier gas and, as noted, the vaporization occurred in a by pass stream, generally of a small proportion as opposed to the main stream. Thus the overall flow is limited and the vaporizing chamber itself must be separate from the main path of the carrier gas passing through the vaporizer.
Accordingly, such present vaporizers are generally large, heavy in mass and are somewhat limited in their ability to provide high flows of an anesthetic laden gas to a desired use.